The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
Many contemporary multi-speed motor vehicle transmissions include a plurality of planetary gear assemblies which have a plurality of fixed connections between the elements of the planetary gear assemblies and a plurality of clutches and brakes also connected to the elements of the planetary gear assemblies that can be selectively and sequentially activated to provide the available gear ratios in an appropriate sequence.
A common component of such transmissions is a cylindrical clutch housing having a hub with male splines or gear teeth at one end and a cylindrical drum section with female splines or gear teeth on an inner surface and a plurality of oil exhaust holes or apertures. Such clutch housings are typically die cast of 380 or 390 aluminum. While this process generates a wholly serviceably component, there are some aspects that can be improved. The die casting process can result in variations and porosity that can lead to cracks, especially in the drum section. If aluminum 390 is utilized to fabricate the housing, the part is stronger than if it were cast of 380 aluminum but because of the hardness of 390 aluminum, the tooling utilized to machine the housing has a shorter service life. As is typical of a complex part, certain areas of the part have higher operational stress than others. If, as is typical, the part is fabricated of one material, such as 380 aluminum, the only way to increase strength in a high stress area is to increase its thickness. This approach will add to the weight and inertia of the part. Alternatively, of course, the entire part could be fabricated of a higher strength material. Another difficulty of a die cast clutch housing is the requirement to drill radially oriented oil exhaust holes in the drum section as they cannot be formed during the die casting process.
From the foregoing, it is apparent that improvements in the configuration and process of fabrication of clutch housings for vehicle transmissions would be desirable. The present invention is so directed.